The solubilization characteristics of DNAPLs by oil-based emulsion

Because of its large surface area and hydrophobicity, a microsized oil emulsion can solubilize dense nonaqueous phase liquids (DNAPLs). When DNAPLs are solubilized by emulsion, they can be removed from the aquifer and their downward migration in the aquifer can be delayed or prevented due to the buoyancy force of the emulsion. Solubilization of DNAPLs was investigated in this study by using an oil-based emulsion prepared via mechanical homogenization of silicone oil. The emulsion droplets that were produced showed similar microsized distribution: the particles in the range of 1-10 μm in diameter were 99% in number distribution and 80% in volume distribution. The oil-based emulsion effectively solubilized trichloroethylene (TCE) and 1,2-dichlorobenzene (DCB) as target pollutants. The emulsion prepared with 2% silicone oil that had been homogenized at 8000 rpm for 15 min could solubilize 99.7% of 7800 ppm DCB and 90.7% of 10,000 ppm TCE. Even the emulsion prepared with a low concentration (0.5%, v/v) of silicone oil removed 99.0% of 7800 ppm DCB from the aqueous phase. Taken together, the results of this study show the potential of the oil-based emulsion as an effective alternative to treat DNAPLs in the aquifer.